Biodegradable polyester composition

ABSTRACT

A biodegradable polyester composition based on a total weight of the biodegradable polyester composition, including a weight content of tetrahydrofuran, which is 3 ppm-200 ppm; and based on the total weight of the biodegradable polyester composition, a weight content of cyclopentanone is 0.5 ppm-85 ppm is provided. The tetrahydrofuran and cyclopentanone is added into the composition and controlling the content of tetrahydrofuran and the content of cyclopentanone in a certain range in the composition to realize printing performance. Moreover, when a velocity of film blowing is 176 Kg/h, a range of a film thickness is less than 0.2 μm and a relative deviation of the film thickness is less than 1%.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCTapplication serial no. PCT/CN2017/074675, filed on Feb. 24, 2017, whichclaims the priority benefit of China application no. 201610126864.7,filed on Mar. 7, 2016. The entirety of each of the abovementioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The present invention belongs to a field of modification ofmacromolecule materials, and specifically relates to a biodegradablepolyester composition with excellent printing performance and bubblestability.

BACKGROUND

Biodegradable polyester is a kind of macromolecule material usingbiological resources as raw materials. With respect to a petroleum-basedpolymer using petrochemical resources as raw materials, thebiodegradable polyester can be degraded during a process of biologicalor biochemical effect or in a biological environment, being a veryactive degradable material in the present biodegradable plastic researchand one of the best degradable materials in market application.

At present, biodegradable polyester film takes one of the most importantapplication fields of biodegradable polyester, mainly including grocerybag, garbage bag, shopping bag, mulching film and the like. During blowmolding process of the biodegradable polyester in preparing films, itfrequently appears that the film is not lubricating enough to adhere toa roll or is too lubricating to roll up. Thus it results in poor bubblestability and a large range of film thickness during film blowing whichseverely affect a continuity of film blowing. In CN 101622311A, byadding 0.05-5 wt % of biodiesel into a biodegradable polyester mixture,a viscosity of the polyester mixture is decreased, to some extentleading to less adherence of film to the roll, which guarantees thecontinuity of film blowing. However, a decrease of the viscosity of thepolyester mixture indicates that an addition of biodiesel damagesperformances of the polyester to some extent, resulting in an increasedmelting index and a decreased viscosity of the polyester mixture.

In addition, during blow molding process of the biodegradable polyesterin preparing films, ink supply is required and thereby a desired labeland a logo are printed on the film. However, during the printing processof biodegradable polyester film, the printing is frequently unreliable(i.e. ink does not fully adhere to the film or an adhesion strength isnot enough) or the printing is excessive (i.e. too much ink adheres tothe film resulting the unclear logo), which indicates poor printingperformance of the film.

The present invention surprisingly finds by research that by adding atrace amount of tetrahydrofuran and cyclopentanone into thebiodegradable polyester composition can prevent the ink from strippingoff the film material during the printing process and prevent excessiveink from adhering to the film material, so that the film shows excellentprinting performance. Moreover, it enables the biodegradable polyesterto have obviously improved film blowing properties. When a velocity offilm blowing is relatively high, it presents good bubble stability aswell as a relatively small range of film thickness and guarantees thecontinuity of a film blowing production.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a biodegradablepolyester composition. By adding a trace amount of tetrahydrofuran andcyclopentanone into the composition, the prepared biodegradablepolyester composition may have excellent printing performance and bubblestability.

The present invention is realized by following technical solution:

a biodegradable polyester composition includes following components inparts by weight:

i) 60 to 100 parts of biodegradable aliphatic-aromatic polyester;

ii) 0 to 40 parts of polylactic acid;

iii) 0 to 35 parts of an organic filler and/or an inorganic filler;

iv) 0 to 1 part of a copolymer which contains epoxy group and is basedon styrene, acrylate and/or methacrylate.

In particular, based on a total weight of the biodegradable polyestercomposition, a weight content of tetrahydrofuran is 3 ppm-200 ppm; andbased on the total weight of the biodegradable polyester composition, aweight content of cyclopentanone is 0.5 ppm-85 ppm.

Preferably, based on the total weight of the biodegradable polyestercomposition, the weight content of tetrahydrofuran is 8 ppm-100 ppm,preferably 15 ppm-75 ppm; and the weight content of cyclopentanone is 5ppm-50 ppm, preferably 10 ppm-35 ppm.

Preferably, the biodegradable polyester composition includes thefollowing components in parts by weight:

i) 65 to 95 parts of the biodegradable aliphatic-aromatic polyester;

ii) 5 to 35 parts of the polylactic acid;

iii) 5 to 25 parts of the organic filler and/or the inorganic filler;

iv) 0.02 to 0.5 part of the copolymer which contains epoxy group and isbased on styrene, acrylate and/or methacrylate.

The biodegradable aliphatic-aromatic polyester is one or more ofpoly(butyleneadipate-co-terephthalate) (PBAT),poly(butylenesuccinate9-co-terephthalate) (PBST) andpoly(butylenesebacate-co-terephthalate) (PBSeT).

Cyclopentanone and tetrahydrofuran added into the biodegradablepolyester composition plays a lubricant-like part. In research, thepresent invention found that controlling the content of tetrahydrofuranas 3 ppm-200 ppm and the content of cyclopentanone as 0.5 ppm-85 ppm inthe biodegradable polyester composition, may enable a coefficient ofkinetic friction for the film material to be within a reasonable range,which prevents the ink from stripping off the film material during theprinting process (i.e. unreliable printing) and prevents excessive inkfrom adhering to the film material, so that the film shows excellentprinting performance. Moreover, a lubrication degree of the film duringthe blow molding process of the biodegradable polyester can be improved.When the velocity of a film blowing is 176 Kg/h, a range of a filmthickness is less than 0.2 μm and a relative deviation of the filmthickness is less than 1%. The bubble stability and continuity of filmblowing are guaranteed.

However, if the content of tetrahydrofuran in the biodegradablepolyester composition is too high, the coefficient of kinetic frictionfor the film is extremely small, resulting in that the printing can't berealized. If the content of tetrahydrofuran is too low, the coefficientof kinetic friction is too large, resulting in that excessive inkadheres to the film during the printing process. If the content ofcyclopentanone in the biodegradable polyester composition is too high,during the film blowing process at high velocity, the film is toolubricating to roll up well on a roll, and also it would results in anunstable film bubble. Therefore, based on the total weight of thebiodegradable polyester composition, the weight content oftetrahydrofuran is preferably 8 ppm-100 ppm, more preferably 15 ppm-75ppm; and the weight content of cyclopentanone is preferably 5 ppm-50ppm, more preferably 10 ppm-35 ppm.

The organic filler is selected from a group consisting of naturalstarch, plasticized starch, modified starch, natural fiber and woodflour, or a mixture thereof. The inorganic filler is selected from agroup consisting of talcum powder, montmorillonite, kaolin, chalk,calcium carbonate, graphite, gypsum, conductive carbon black, calciumchloride, ferric oxide, dolomite, silicon dioxide, wollastonite,titanium dioxide, silicate, mica, glass fiber and mineral fiber, or amixture thereof.

A route of acquiring tetrahydrofuran and cyclopentanone in the presentinvention may be by means of adding tetrahydrofuran and cyclopentanonedirectly during blending, extruding and processing the biodegradablepolyester composition.

According to different needs of use, the biodegradable polyestercomposition according to the present invention may be further added with0 to 4 parts of at least one of following substances: plasticizer,release agent, surfactant, wax, antistatic agent, pigment, UV absorbent,UV stabilizer or other plastic additives.

The plasticizer is one of or a mixture of two or more of citric esters,glycerol, epoxidized soybean oil and the like.

The release agent is one of or a mixture of two or more of silicone oil,paraffin, white mineral oil and Vaseline.

The surfactant is one of or a mixture of two or more of polysorbate,palmitate and laurate.

The wax is one of or a mixture of two or more of erucamide, stearamide,behenamide, beeswax and beeswax ester.

The antistatic agent is a permanent antistatic agent, specificallylisted as one of or a mixture of two or more of PELESTAT-230,PELESTAT-6500 and SUNNICO ASA-2500.

The pigment is one of or a mixture of two or more of carbon black, blackmasterbatch, titanium dioxide, zinc sulfide, phthalocyanine blue andfluorescent orange.

The UV adsorbent is one or more of UV-944, UV-234, UV-531 and UV-326.

The UV stabilizer is one or more of UV-123, UV-3896 and UV-328.

The other plastic additives may be nucleating agent, antifogging agentand the like.

The biodegradable polyester composition according to the presentinvention may be used for preparing shopping bag, compost bag, mulchingfilm, protective cover film, silo film, film strip, fabric, non-fabric,textile, fishing net, bearing bag, garbage bag and the like.

Compared to the prior art, the present invention has followingbeneficial effects:

In the present invention, by adding tetrahydrofuran and cyclopentanoneinto the composition and controlling the content of tetrahydrofuran in arange of 3 ppm-200 ppm and the content of cyclopentanone in a range of0.5 ppm-85 ppm in the composition, not only poor printing of thebiodegradable polyester composition during the printing process may behugely improved, neither the ink stripping off the film material, norexcessive ink adhering to the film material, so that the film showsexcellent printing performance. Moreover, the lubrication degree of filmduring a blow molding process of the biodegradable polyester can beimproved. When the velocity of film blowing is 176 Kg/h, the range ofthe film thickness is less than 0.2 μm and the relative deviation of thefilm thickness is less than 1%. The bubble stability and the continuityof film blowing are guaranteed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be further described below by way of specificimplementations, and the following embodiments are preferredimplementations of the present invention, but the implementations of thepresent invention are not limited by the following embodiments.

In the embodiments of the present invention, PBAT is chosen as acomponent i); ADR4370 is chosen as a component iv); starch is chosen asan organic filler; talcum powder and calcium carbonate are chosen asinorganic filler; citric esters is chosen as a plasticizer; palmitate ischosen as a surfactant; and stearamide is chosen as a wax. Theabove-mentioned promoters, PBAT, ADR4370, PLA, tetrahydrofuran andcyclopentanone are commercially available.

Embodiments 1-16 and Comparative Embodiments 1-4

According to formulae shown in Table 1, PBAT, PLA, ADR4370, organicfillers, inorganic fillers, promoters such as plasticizer, surfactant,wax and the like, tetrahydrofuran and cyclopentanone were mixed evenlyand put into a single screw extruder. After being extruded at 140°C.-240° C. and prilled, the compositions were obtained. Data ofperformance tests is shown in Table 1.

Performance Evaluation Method:

(1) Evaluation Method for Printing Performance of a BiodegradablePolyester Composition:

Biodegradable polyester compositions with different printing effectswere taken. Based on clarity of a printed label and adherence of ink toa surface of a film, different printing effects were ranked according tofollowing method:

level 1: the label is clear and there is no excessive ink adhering tothe film;

level 2: the label is clear but there is a little excessive ink adheringto the film;

level 3: the label is basically clear but there is much ink adhering tothe film;

level 4: the label is obscure and there is abundant ink adhering to thefilm;

level 5: the label can't be shown and there is no ink adhering to thefilm.

(2) Evaluation Method for Bubble Stability of the BiodegradablePolyester Composition:

The bubble stability of the biodegradable polyester composition duringfilm blowing was evaluated by a method of a range of a film thicknessand a relative deviation of the film thickness:

The film thickness was measured via a screw micrometer: 10 measurementpoints were taken evenly on a film of 1 m*1 m to measure the filmthickness.

The range of the film thickness was a difference value between a maximumthickness and a minimum thickness among the 10 measurement points.

The relative deviation of the film thickness was calculated according tothe following formula:

${{relative}\mspace{14mu}{deviation}\mspace{14mu}{of}\mspace{14mu}{film}\mspace{14mu}{thickness}\mspace{14mu}\%} = {\frac{{range}\mspace{14mu}{of}\mspace{14mu}{film}\mspace{14mu}{thickness}}{{average}\mspace{14mu}{film}\mspace{14mu}{thickness}} \times 100\%}$

wherein, the average film thickness was calculated as an arithmeticaverage of the thicknesses measured respectively at the 10 measurementpoints which were taken evenly on the film of 1 m*1 m.

(3) Determination Method for Tetrahydrofuran:

Drawing of a Standard Curve of Tetrahydrofuran:

Tetrahydrofuran/methanol solutions in concentrations of 0.010 g/L, 0.1g/L, 1.0 g/L, 5.0 g/L, 10.0 g/L, 20.0 g/L, 50.0 g/L and 100.0 g/L wereprepared, respectively. Peak areas of tetrahydrofuran in thetetrahydrofuran/methanol solutions in different concentrations weremeasured respectively by a static headspace method. The standard curveof tetrahydrofuran was drawn, with the peak area of tetrahydrofuran asan ordinate and the concentration of tetrahydrofuran as an abscissa.

Measurement of a Content of Tetrahydrofuran in the BiodegradablePolyester Composition:

Approximate 1.2000 g of biodegradable polyester composition was weighedaccurately and put into a static headspace test flask; the peak area oftetrahydrofuran in the biodegradable polyester composition was measuredby the static headspace method; and the content of tetrahydrofuran inthe biodegradable polyester composition was calculated according to thepeak area of tetrahydrofuran in the biodegradable polyester compositionand the standard curve of tetrahydrofuran. The standard curve wascalibrated by the tetrahydrofuran/methanol solution.

Conditions for Static Headspace Test are as Follows:

Temperature:

Heater: 105° C.

Quantitative loop: 135° C.

Transmission line: 165° C.

Time:

Balance for sample bottle: 120 minutes

Duration for sample injection: 0.09 minute

GC circulation: 30 minutes.

Instrument models and parameters for static headspace are as follows:

Agilent Technologies 7697 Headspace Sampler;

Agilent Technologies 7890 AGC System;

Chromatographic column: J&W 122-7032: 250° C.: 30 m×250 μm×0.25 μm

Sample injection: front SS injection port N₂

Sample production: front detector FID.

(4) Determination Method for Cyclopentanone:

1) Drawing of a Standard Curve of Cyclopentanone:

Cyclopentanone/methanol solutions in concentrations of 0.0001 g/L, 0.001g/L, 0.01 g/L, 0.1 g/L, 5.0 g/L, 10.0 g/L and 20.0 g/L were prepared,respectively. Peak areas of cyclopentanone in thecyclopentanone/methanol solutions in different concentrations weremeasured respectively by the static headspace method. The standard curveof cyclopentanone was drawn, with the peak area of cyclopentanone as theordinate and the concentration of cyclopentanone as the abscissa.

2) Measurement of a Content of Cyclopentanone in the BiodegradablePolyester Composition:

Approximate 1.2000 g of biodegradable polyester composition was weighedaccurately and put into a static headspace test flask; the peak area ofcyclopentanone in the biodegradable polyester composition was measuredby the static headspace method; and the content of cyclopentanone in thebiodegradable polyester composition was calculated according to the peakarea of cyclopentanone in the biodegradable polyester composition andthe standard curve of cyclopentanone.

Instrument models and parameters for static headspace are as follows:

Agilent Technologies 7697 Headspace Sampler;

Agilent Technologies 7890A GC System;

Chromatographic column: J&W 122-7032: 250° C.: 30 m×250 μm×0.25 μm

Sample injection: front SS injection port N₂

Sample production: front detector FID.

Conditions for static headspace test are as follows:

Temperature:

Heater: 105° C.

Quantitative loop: 135° C.

Transmission line: 165° C.

Time:

Balance for sample bottle: 120 minutes

Duration for sample injection: 0.09 minute

GC circulation: 30 minutes.

TABLE 1 Test data of Comparative Embodiments 1-4 and Embodiments 1-16(parts by weight) Compar- Compar- Compar- Compar- ative ative ativeative Embodi- Embodi- Embodi- Embodi- Embodi- Embodi- Embodi- Embodi-Embodi- Embodi- Embodi- ment 1 ment 2 ment 3 ment 4 ment 1 ment 2 ment 3ment 4 ment 5 ment 6 ment 7 PBAT 84.1 84.1 84.1 84.1 100 84.1 84.1 84.184.1 67 66.5 PLA 10 10 10 10 10 10 10 10 15 32 starch 17 talcum powder1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 calcium carbonate 3.5 3.5 3.5 3.5 3.53.5 3.5 3.5 ADR4370 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.5 citricesters 0.2 palmitate 0.5 stearamide 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.50.5 content of tetra- 1 227 15 81 200 15 19 21 38 44 75 hydrofuran(based on the whole composition)/ppm content of cyclo- 0 117 10 38 10 1012 17 23 30 35 pentanone (based on the whole composition)/ppm level ofprinting 4 5 2 2 3 1 1 1 1 1 1 performance extrusion 176 176 125 200 176176 176 176 176 176 176 velocity at film blowing/Kg/h range of film 0.310.42 0.21 0.29 0.19 0.10 0.10 0.14 0.15 0.13 0.15 thickness/μm relativedevia- 1.5 2.1 1.12 1.93 0.92 0.42 0.43 0.55 0.61 0.62 0.69 tion of filmthickness/% Embodi- Embodi- Embodi- Embodi- Embodi- Embodi- Embodi-Embodi- ment 9 ment 10 ment 11 ment 12 ment 13 ment 14 ment 15 ment 16PBAT 84.1 84.1 84.1 84.1 84.1 84.1 84.1 84.1 PLA 10 10 10 10 10 10 10 10starch talcum powder 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 calcium carbonate3.5 3.5 3.5 3.5 3.5 3.5 3.5 3.5 ADR4370 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3citric esters palmitate stearamide 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5content of tetra- 8 12 81 100 3 5 167 200 hydrofuran (based on the wholecomposition)/ppm content of cyclo- 6 8 38 50 1 4 62 85 pentanone (basedon the whole composition)/ppm level of printing 2 2 2 2 3 3 3 3performance extrusion 176 176 176 176 176 176 176 176 velocity at filmblowing/Kg/h range of film 0.16 0.15 0.17 0.17 0.19 0.18 0.19 0.19thickness/μm relative devia- 0.81 0.74 0.83 0.84 0.98 0.89 0.90 0.95tion of film thickness/%

It can be seen from Table 1 that, in the biodegradable polyestercomposition, when the content of tetrahydrofuran is 3-200 ppm and thecontent of cyclopentanone is 0.5-85 ppm, the level of printingperformance can reach above level 3, which indicates that thecomposition has excellent printing performance. In addition, when thevelocity at film blowing is 176 Kg/h, the range of the film thickness isless than 0.2 μm and the relative deviation of the film thickness isless than 1%. It indicates that the composition has better bubblestability. However, in Comparative Embodiment 1, in which the content oftetrahydrofuran is less than 3 ppm and the content of cyclopentanone is0, the level of printing performance of the composition is level 4, therange of the film thickness is more than 0.2 m, and the relativedeviation of the film thickness is more than 1%. In ComparativeEmbodiment 2, in which the content of tetrahydrofuran is more than 200ppm and the content of cyclopentanone is more than 85 ppm, the level ofprinting performance of the composition is level 5, the range of thefilm thickness is more than 0.2 μm, and the relative deviation of thefilm thickness is more than 1%, which indicates that the printingperformance and the bubble stability of the composition are rather poor.In Comparative Embodiment 3, in which the velocity at film blowing islower than 176 Kg/h and in Comparative Embodiment 4, in which thevelocity at film blowing is higher than 176 Kg/h, the range of the filmthickness is more than 0.2 μm and the relative deviation of the filmthickness is more than 1%. It indicates that the film bubble of thecomposition is unstable either.

What is claimed is:
 1. A biodegradable polyester composition, comprisingthe following components in parts by weight: i) 60 to 100 parts ofbiodegradable aliphatic-aromatic polyester; ii) 0 to 40 parts ofpolylactic acid; iii) 0 to 35 parts of an organic filler and/or aninorganic filler; iv) 0 to 1 part of a copolymer which contains epoxygroup and is based on styrene, acrylate and/or methacrylate; wherein,based on a total weight of the biodegradable polyester composition, aweight content of tetrahydrofuran is 3 ppm-200 ppm; and based on thetotal weight of the biodegradable polyester composition, a weightcontent of cyclopentanone is 0.5 ppm-85 ppm.
 2. The biodegradablepolyester composition according to claim 1, wherein based on the totalweight of the biodegradable polyester composition, the weight content oftetrahydrofuran is 8 ppm-100 ppm; and the weight content ofcyclopentanone is 5 ppm-50 ppm.
 3. The biodegradable polyestercomposition according to claim 1, comprising the following components inparts by weight: i) 65 to 95 parts of the biodegradablealiphatic-aromatic polyester; ii) 5 to 35 parts of the polylactic acid;iii) 5 to 25 parts of the organic filler and/or the inorganic filler;iv) 0.02 to 0.5 part of the copolymer which contains epoxy group and isbased on styrene, acrylate and/or methacrylate.
 4. The biodegradablepolyester composition according to claim 1, wherein the weight contentof tetrahydrofuran is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of tetrahydrofuran in thebiodegradable polyester composition is measured by a static headspacemethod; the content of tetrahydrofuran in the biodegradable polyestercomposition is calculated according to the peak area of tetrahydrofuranin the biodegradable polyester composition and a standard curve oftetrahydrofuran; and the standard curve of tetrahydrofuran is calibratedby a solution of tetrahydrofuran/methanol; the weight content ofcyclopentanone is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of cyclopentanone in thebiodegradable polyester composition is measured by the static headspacemethod; the content of cyclopentanone in the biodegradable polyestercomposition is calculated according to the peak area of cyclopentanonein the biodegradable polyester composition and a standard curve ofcyclopentanone; and the standard curve of cyclopentanone is calibratedby a solution of cyclopentanone/methanol.
 5. The biodegradable polyestercomposition according to claim 1, wherein the biodegradablealiphatic-aromatic polyester is one or more ofpoly(butyleneadipate-co-terephthalate) (PBAT),poly(butylenesuccinate-co-terephthalate) (PBST) andpoly(butylenesebacate-co-terephthalate) (PBSeT).
 6. The biodegradablepolyester composition according to claim 1, wherein the organic filleris selected from a group consisting of natural starch, plasticizedstarch, modified starch, natural fiber and wood flour, or a mixturethereof; and the inorganic filler is selected from a group consisting oftalcum powder, montmorillonite, kaolin, chalk, calcium carbonate,graphite, gypsum, conductive carbon black, calcium chloride, ferricoxide, dolomite, silicon dioxide, wollastonite, titanium dioxide,silicate, mica, glass fiber and mineral fiber, or a mixture thereof. 7.The biodegradable polyester composition according to claim 1, furthercomprising 0 to 4 parts of at least one of following substances:plasticizer, release agent, surfactant, wax, antistatic agent, pigment,UV absorbent, UV stabilizer or other plastic additives.
 8. Thebiodegradable polyester composition according to claim 1, wherein alevel of printing performance of the biodegradable polyester compositionreaches to level 3 or above.
 9. The biodegradable polyester compositionaccording to claim 1, wherein when an extrusion velocity at film blowingof the biodegradable polyester composition is 176 Kg/h, a range of afilm thickness is less than 0.2 μm and a relative deviation of the filmthickness is less than 1%.
 10. The biodegradable polyester compositionaccording to claim 2, comprising the following components in parts byweight: i) 65 to 95 parts of the biodegradable aliphatic-aromaticpolyester; ii) 5 to 35 parts of the polylactic acid; iii) 5 to 25 partsof the organic filler and/or the inorganic filler; iv) 0.02 to 0.5 partof the copolymer which contains epoxy group and is based on styrene,acrylate and/or methacrylate.
 11. The biodegradable polyestercomposition according to claim 2, wherein the weight content oftetrahydrofuran is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of tetrahydrofuran in thebiodegradable polyester composition is measured by a static headspacemethod; the content of tetrahydrofuran in the biodegradable polyestercomposition is calculated according to the peak area of tetrahydrofuranin the biodegradable polyester composition and a standard curve oftetrahydrofuran; and the standard curve of tetrahydrofuran is calibratedby a solution of tetrahydrofuran/methanol; the weight content ofcyclopentanone is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of cyclopentanone in thebiodegradable polyester composition is measured by the static headspacemethod; the content of cyclopentanone in the biodegradable polyestercomposition is calculated according to the peak area of cyclopentanonein the biodegradable polyester composition and a standard curve ofcyclopentanone; and the standard curve of cyclopentanone is calibratedby a solution of cyclopentanone/methanol.
 12. The biodegradablepolyester composition according to claim 3, wherein the weight contentof tetrahydrofuran is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of tetrahydrofuran in thebiodegradable polyester composition is measured by a static headspacemethod; the content of tetrahydrofuran in the biodegradable polyestercomposition is calculated according to the peak area of tetrahydrofuranin the biodegradable polyester composition and a standard curve oftetrahydrofuran; and the standard curve of tetrahydrofuran is calibratedby a solution of tetrahydrofuran/methanol; the weight content ofcyclopentanone is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of cyclopentanone in thebiodegradable polyester composition is measured by the static headspacemethod; the content of cyclopentanone in the biodegradable polyestercomposition is calculated according to the peak area of cyclopentanonein the biodegradable polyester composition and a standard curve ofcyclopentanone; and the standard curve of cyclopentanone is calibratedby a solution of cyclopentanone/methanol.
 13. The biodegradablepolyester composition according to claim 10, wherein the weight contentof tetrahydrofuran is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of tetrahydrofuran in thebiodegradable polyester composition is measured by a static headspacemethod; the content of tetrahydrofuran in the biodegradable polyestercomposition is calculated according to the peak area of tetrahydrofuranin the biodegradable polyester composition and a standard curve oftetrahydrofuran; and the standard curve of tetrahydrofuran is calibratedby a solution of tetrahydrofuran/methanol; the weight content ofcyclopentanone is measured by following method: 1.2000 g of thebiodegradable polyester composition is weighed accurately and added intoa static headspace test flask; a peak area of cyclopentanone in thebiodegradable polyester composition is measured by the static headspacemethod; the content of cyclopentanone in the biodegradable polyestercomposition is calculated according to the peak area of cyclopentanonein the biodegradable polyester composition and a standard curve ofcyclopentanone; and the standard curve of cyclopentanone is calibratedby a solution of cyclopentanone/methanol.
 14. The biodegradablepolyester composition according to claim 2, wherein the biodegradablealiphatic-aromatic polyester is one or more ofpoly(butyleneadipate-co-terephthalate) (PBAT),poly(butylenesuccinate-co-terephthalate) (PB ST) andpoly(butylenesebacate-co-terephthalate) (PBSeT).
 15. The biodegradablepolyester composition according to claim 3, wherein the biodegradablealiphatic-aromatic polyester is one or more ofpoly(butyleneadipate-co-terephthalate) (PBAT),poly(butylenesuccinate-co-terephthalate) (PBST) andpoly(butylenesebacate-co-terephthalate) (PBSeT).
 16. The biodegradablepolyester composition according to claim 10, wherein the biodegradablealiphatic-aromatic polyester is one or more ofpoly(butyleneadipate-co-terephthalate) (PBAT),poly(butylenesuccinate-co-terephthalate) (PBST) andpoly(butylenesebacate-co-terephthalate) (PBSeT).
 17. The biodegradablepolyester composition according to claim 2, wherein the organic filleris selected from a group consisting of natural starch, plasticizedstarch, modified starch, natural fiber and wood flour, or a mixturethereof; and the inorganic filler is selected from a group consisting oftalcum powder, montmorillonite, kaolin, chalk, calcium carbonate,graphite, gypsum, conductive carbon black, calcium chloride, ferricoxide, dolomite, silicon dioxide, wollastonite, titanium dioxide,silicate, mica, glass fiber and mineral fiber, or a mixture thereof. 18.The biodegradable polyester composition according to claim 3, whereinthe organic filler is selected from a group consisting of naturalstarch, plasticized starch, modified starch, natural fiber and woodflour, or a mixture thereof; and the inorganic filler is selected from agroup consisting of talcum powder, montmorillonite, kaolin, chalk,calcium carbonate, graphite, gypsum, conductive carbon black, calciumchloride, ferric oxide, dolomite, silicon dioxide, wollastonite,titanium dioxide, silicate, mica, glass fiber and mineral fiber, or amixture thereof.
 19. The biodegradable polyester composition accordingto claim 10, wherein the organic filler is selected from a groupconsisting of natural starch, plasticized starch, modified starch,natural fiber and wood flour, or a mixture thereof; and the inorganicfiller is selected from a group consisting of talcum powder,montmorillonite, kaolin, chalk, calcium carbonate, graphite, gypsum,conductive carbon black, calcium chloride, ferric oxide, dolomite,silicon dioxide, wollastonite, titanium dioxide, silicate, mica, glassfiber and mineral fiber, or a mixture thereof.
 20. The biodegradablepolyester composition according to claim 2, further comprising 0 to 4parts of at least one of following substances: plasticizer, releaseagent, surfactant, wax, antistatic agent, pigment, UV absorbent, UVstabilizer or other plastic additives.
 21. The biodegradable polyestercomposition according to claim 3, further comprising 0 to 4 parts of atleast one of following substances: plasticizer, release agent,surfactant, wax, antistatic agent, pigment, UV absorbent, UV stabilizeror other plastic additives.
 22. The biodegradable polyester compositionaccording to claim 10, further comprising 0 to 4 parts of at least oneof following substances: plasticizer, release agent, surfactant, wax,antistatic agent, pigment, UV absorbent, UV stabilizer or other plasticadditives.
 23. The biodegradable polyester composition according toclaim 2, wherein a level of printing performance of the biodegradablepolyester composition reaches to level 3 or above.
 24. The biodegradablepolyester composition according to claim 4, wherein a level of printingperformance of the biodegradable polyester composition reaches to level3 or above.
 25. The biodegradable polyester composition according toclaim 11, wherein a level of printing performance of the biodegradablepolyester composition reaches to level 3 or above.
 26. The biodegradablepolyester composition according to claim 2, wherein when an extrusionvelocity at film blowing of the biodegradable polyester composition is176 Kg/h, a range of a film thickness is less than 0.2 μm and a relativedeviation of the film thickness is less than 1%.
 27. The biodegradablepolyester composition according to claim 4, wherein when an extrusionvelocity at film blowing of the biodegradable polyester composition is176 Kg/h, a range of a film thickness is less than 0.2 μm and a relativedeviation of the film thickness is less than 1%.
 28. The biodegradablepolyester composition according to claim 11, wherein when an extrusionvelocity at film blowing of the biodegradable polyester composition is176 Kg/h, a range of a film thickness is less than 0.2 μm and a relativedeviation of the film thickness is less than 1%.
 29. The biodegradablepolyester composition according to claim 1, wherein based on the totalweight of the biodegradable polyester composition, the weight content oftetrahydrofuran is 15 ppm-75 ppm; and the weight content ofcyclopentanone is 10 ppm-35 ppm.